The problem of vehicles, such as trucks, hitting overhead obstructions has become greater in recent years.
The frequency of this problem occurring has increased for a variety of reasons.
First, there is a greater amount of truck traffic on the nation's highways, owing to the continued switching of railroad freight to truck freight. Hence, a greater number of trucks on the road equals a greater number of accidents involving the roofs of the truck trailer body hitting a low bridge, for example.
Second, there is an increased use of independent truckers who own their own cabs. Such truckers frequently drive cargo in trailers of varying heights. Accordingly, if a trucker is not familiar with the actual height of the trailer he or she is driving, or is unaware that the trailer has a higher than standard height, the potential for an accident involving hitting an overhead object increases.
Third, the infrastructure of highways and bridges has been allowed to deteriorate owing to budgetary constraints on the local, state, and federal level. Thus, older bridges abound which frequently are relatively low compared to recently constructed bridges.
Truckers unfamiliar with such older, lower bridges often run into them with the body of the trailer they are trucking. Further, such older bridges were often constructed having arched supports, which arched supports have a highest point above the ground in the middle of the bridge over the roadway passing underneath the bridge, and a lower point at each of the far left and right side termination points of the curvature of the arch. This arch construction itself poses a couple of problems; namely, the trucker may be familiar with modern bridges having a substantially horizontal, fixed bridge height relative to the road underneath, and may not appreciate that arched bridges present an obstacle of varied height. In addition, given that vehicles travel in the right lane in most countries, and given the typical location of the steering wheel of the truck in the left side of the truck cab in such countries, the driver of the truck is seated nearer to the high point of such arched bridges, while to the right of the trucker, the arched bridge presents a lower profile which may be lower than the roof line of the right side of the trailer body.
Finally, given budget restraints many bridges have no bridge heights posted on them, as lost and stolen height indicator signs are often not been timely replaced.
Earlier systems for avoiding collisions between vehicles and overhead obstructions have attempted to eliminate the problem in a variety of ways.
U.S. Pat. No. 3,232,265 to Hurt discloses a height clearance indicator which includes a flexible, antenna-like height indicator which physically contacts an overhead object and provides a relatively direct indication of the height of the object by mechanical means. Although the Hurt clearance indicator is useful owing to its functioning without an electrical supply, a drawback of this device is that it will wear over time given its direct physical contact with obstructions.
U.S. Pat. No. 4,284,971 to Lowry et al. discloses an overheight vehicle detection and warning system which is installed along a roadway, measures the vehicle height as it passes the system, and illuminates a warning sign telling the driver of the truck to stop if the vehicle height is greater than an approaching bridge. Not only is this system complicated, and expensive, but it must reliably determine the height of moving vehicles. Although the Lowry system provides a standby electrical system to warn the vehicle operator that the height measurement system is not operating, if such is the case, the vehicle operator must make his or her own decision as to whether the upcoming bridge is sufficiently high to drive underneath.
There have been applications of ultrasonic waves in conjunction with collecting data about vehicles.
U.S. Pat. No. 4,789,941 to Nunberg discloses another road-based system which is a computerized vehicle classification system that calculates the height of the vehicle in order to classify the vehicle for toll collection or traffic control purposes. The Nunberg system is inapplicable for determining the absolute heights of vehicles, as this system rejects the height of the vertical exhaust pipe of a truck, for example, as an anomalous reading because Nunberg is not concerned with the absolute height of vehicles, but rather with the classification of the vehicle.
German Auslegeschrift 1,218,194 discloses the use of ultrasonic waves transmitted and received by transducers located on the underside of an arched post under which a vehicle passes. This system simply considers the rate at which pulse intervals are received for determining whether a vehicle traveling at a particular speed is following the previous vehicle too closely. No vehicle height data is generated.
U.S. Pat. No. 5,076,384 to Wada et al. discloses an ultrasonic obstacle sensor including an ultrasonic transmitter mounted on a vehicle for transmitting ultrasonic waves toward the road surface, and an ultrasonic receiver for receiving ultrasonic waves reflected from the road surface, whereby the received signal is compared with a reference signal to detect components in the received signal corresponding to obstacles on the road surface. The information collected about the road obstacles is used to control the stiffness of the vehicle suspension.
U.S. Pat. No. 4,015,232 to Sindle discloses an ultrasonic distance detector for vehicles that tells the driver how close portions of the vehicle are to horizontally spaced objects. Sindle describes the mounting of ultrasonic sensing devices around the vehicle, preferably on external vertical surfaces, such as the face of a front bumper for determining how close the vehicle's bumper is to a wall.
U.S. Pat. No. 5,028,920 to Dombrowski discloses a microwave radar device mountable on the rear of a truck that uses the doppler shift principle to detect the presence of a moving target within the transceiver range so that the truck driver is alerted to the presence of objects behind the truck which are moving relative to the truck. Dombrowski discloses a housing which is diagonally sectioned to provide a pivotable top cover. The wave output from the Dombrowski transceiver is transmitted outwardly through a rearwardly protruding channel section on the rear wall of the housing. Dombrowski makes no mention of any movement of the housing when the alerting device is in use, and presumably the microwaves pass through the walls of the housing.
Accordingly, there is a need for a simply, accurate device which can be mounted on the vehicle itself to provide obstacle height information to the driver of the vehicle.
The use of the terms "vehicle" and "truck" is for convenience only, as all types of vehicles and moving objects which move relative to overhead objects, such as recreational vehicles (RVs), airplanes moving into hangars, and ships passing beneath bridges, are intended to be within the scope of the invention.